The present invention relates to channel estimation of a Mobile Station (MS) in a communication system. More specifically, the present invention relates to a method and system for channel estimation of a MS in presence of co-channel interference, to improve the performance of sector combining.
In a cellular like communication system, sectorization is used as a technique to increase the coverage and capacity of the system or network. A Base Station Transceiver (BTS) comprises multiple sectors, typically 3 sectors are used in a single BTS. A MS is served by a sector of a BTS in which the MS is located in. Each sector of a BTS has information to decode signals received from MSs served by it. The signals may be demodulated at the sector by multiplying the received signal by a pseudo random binary sequence (PRBS) (de-PRBS) which corresponds to the sector. Each sector may use a different PRBS for demodulating its signals. The signals from a MS may be received at one or more collocated or adjacent sectors of a BTS. The signals received at the sector and one or more collocated sectors of the same BTS may be received with different power levels due to different pathloss, shadowing and the angle that the MS makes with the boresight of sector antenna. Therefore, sector combining may be performed to combine the signals received from the MS at the BTS from multiple sectors, which improves the decoding reliability of the signal received from the MS. To achieve sector combining, the channel of the MS has to be estimated at the sectors of the same BTS. The signal received from the MS at one or more collocated sectors may be interfered by a signal received from one or more interfering MSs, which reduces the quality of channel estimation for the MS at one or more collocated sectors. As a result, the link performance of sector combining degrades.